Mitochondria play a critical role in the energy homeostasis of the cell and the intact animal. Mitochondria oxidize substrates such as lipids and glucose, thereby serving as a central control point for fuels which are dysregulated in human type 2 diabetes. Recent data suggests that human type-2 diabetes is associated with lower expression of the mitochondrial OXPHOS system and their regulators, the PGC-1 coactivators, in muscle. Our recent unpublished genetic data clearly indicate that reduced PGC-1a levels in muscle can cause abnormal glucose tolerance, even in the heterozygous KO state. We propose here an integrated approach to develop chemical compounds that can modulate the PGC-1 coactivators and/or mitochondrial function in both cells and animals. The goal is to establish proof of concept that chemical manipulations of these systems can have a benefit in obesity and type-2 diabetes. We will utilize chemical libraries that include a large number of FDA-approved drugs and drug-like compounds, as well as novel chemical libraries produced at the Broad Institute. We will also investigate molecular targets of novel compounds where the target is not known, using a novel method involving the use of recombinant yeast strains. Specific Aim 1 will utilize mitochondrial-based screens to find compounds that can control mitochondria number, membrane potential and ATP synthesis. Specific Aim 2 will perform screens that will identify compounds that modulate the expression of PGC-1a and PGC-1beta, and their function in mitochondrial biology. Specific Aim 3 will utilize a novel method using recombinant yeast strain to identify targets that are being altered by novel chemical matter arising from Aims 1 and 2. In all cases, we will use cell-based screens of mitochondrial function and insulin-resistance. In addition, we will test the compounds arising from these screens in well-established animal models of obesity, insulin resistance and type-2 diabetes. All of these projects will make use of chemical screening at the Broad Institute and the animal resources at the DFCI. Together, this highly integrated and collaborative project has a high likelihood of providing proof of concept for a novel avenue to the therapeutics of obesity and diabetes.